Mobile electronic devices, such as smart phones, tablet devices, or the like, includes charge connectors that are used to charge batteries, via external power supplies, included in the mobile electronic devices. A charging terminal of a charge connector is brought into contact with a charging terminal of a battery charger, thereby a battery is charged. An example of the battery charger includes a cradle that includes a charging terminal. A mobile electronic device is placed on a cradle that is connected to an external power supply and both charging terminals are brought into contact with each other, thereby the battery is charged.
Related-art examples are described, for example, in Japanese Laid-open Patent Publication No. 2004-194481 and Japanese Laid-open Patent Publication No. 10-327536.
For example, if a charging terminal is dirty or if a mobile electronic device is diagonally placed on a cradle and both charging terminals are brought into contact at a position that is shifted from a normal contact position, the resistance at the contact point in which the charging terminal of the battery charger is brought into contact with the charging terminal of the charge connector becomes large. Hereinafter, the resistance at the contact point in which the charging terminal of the battery charger is brought into contact with the charging terminal of the charge connector may sometimes be referred to as the “contact resistance”. If charging is performed in such a state in which the contact resistance is large, the electric power consumed at the contact portion becomes large and thus heat is generated from the charging terminal. In recent years, with an increase in the capacity of a battery mounted on a mobile electronic device, in order to reduce the charging time, charging is performed by using high electric current. If the charging is performed by using high electric current when the contact resistance is large, an amount of heat generated in the charging terminal becomes great, which is dangerous. For example, if the amount of heat generated in the charging terminal becomes great, a casing of the mobile electronic device may sometimes be melted.